1. Field of the Invention
The present invention relates to a rectification device, particularly to a silicon-controlled rectification device with high efficiency.
2. Description of the Related Art
Because the IC device sizes have been shrunk to nanometer scale, the consumer electronics, like the laptop and mobile devices, have been designed to be much smaller than ever. Without suitable protection devices, the functions of these electronics could be reset or even damaged under ESD (Electrostatic Discharge) events. ESD devices are used in many integrated circuits to discharge high voltage received by external pins before the high voltage damages internal devices. One type of ESD devices uses an SCR (silicon-controlled rectifier).
FIG. 1 shows such a conventional SCR ESD device, which includes: an N well 10 and a P well 12 located in a P substrate 14, a high density P+ doped region 16 and a high density N+ doped region 18 located in the N well 10, and a high density P+ doped region 20 and a high density N+ doped region 22 located in the P well 12. In this SCR ESD device, the P+ doped region 16, the N+ doped region 18, the N well 10, and the P well 12 constitute a PNP transistor; the N well 10, the P well 12, and the N+ doped region 22 constitute an NPN transistor. An external pad, PAD, is coupled to the P+ doped region 16 and the N+ doped region 18, and, an external grounding pad, GND, is coupled to the P+ doped region 20 and the N+ doped region 22. Therefore, when the PAD receives a high voltage, the SCR ESD device is triggered to conduct a current to the GND. However, the trigger voltage and the holding voltage of this SCR are fixed. This design does not provide adjustable trigger voltage and holding voltage to satisfy the requirement of ESD protection. In addition, the ESD current of the SCR is not uniformly distributed which results in low ESD efficiency.
To overcome the abovementioned problems, the present invention provides a silicon-controlled rectification device with high efficiency, so as to solve the afore-mentioned problems of the prior art.